Device for illuminating microscopic objects



'J l 2, a. GERSTENBERGE'R EI'AL 2,206,180

DEVICE FOR ILLUMINATING MICROSCOPIC OBJECTS Filed 001'. I9, 1937 I Inventors:

PatentedJuly 2, 1940 UNITED STATES PATENT OFFICE Bruno Gerstenberger, Max

Robert Richter, Jena,

Hiibschmann, and Germany, assign! to the firm Carl Zeiss, Jena, Germany Application October 19, 1937, Serial No. 169,798 In Germany October 28, 1936 '2 Claims. (on. sat-'39) An application has October 28, 1936. a 1 The invention has reference to a device for illuminating microscopic objects which comprises a source of light, a lamp condensenan additional optical system displaceable entirely or partly along the optical axis of the path of the illumination rays and a microscope condenser, the device concerned being'of the kind which illumihates the objects by transmitted light. In the known constructional form of the illumination device, the optical parts have a common housing which can ,be placed into the holder of the con denser of a microscope and contains a reflecting system for bending .the.path of the illumination rays at right angles; The number of the optical elements used and the necessity of these elements having definite distances apart make the device comparatively unwieldy. The device extends to considerably outside the margin of the object stage and handicaps microscoping when the bracket of the microscope stand is tobe remote from the observer.

The invention, which aims at overcomingthis disadvantage, dispenses with the said common housingand provides that the device consists of two separate constructional parts,v the one of these parts, which comprises the source of light and the lamp condenser, being disposed in the base'of the microscope, and the other of these parts, which comprises the pancratic reversing system and the microscope condenser, being fixed to that portion of the microscope stand which is above the base and below the stage. This other part is conveniently displaceable along the optical axis.

To use the same source of light also in darkfield microscopy, that part of the illumination device which is fixed above the base to the microscope stand is conveniently interchangeable with another condenser. This interchange. need not, of course, be restricted to dark-field condensers but can be applied as wel in the case of light-field condensers notpermitting pancratic alterations in the illumination.

The knownlllumination device has, as a rule, a changeable diaphragm restricting the aperture of the pencil of illumination rays. A diaphragm of this kind is conveniently used also in devices constructed according to the invention. This diaphragm is preferably liked to a support detachably so connected to the part in the microscope base as to constitute a slide which is similar to the sliding object changer frequently used in microscopes and can be displacedin a been filed in Germany,

corresponding guide in the microscope base. The diaphragm can, accordingly, be removed from the ray path by a single manipulation when it is not required any longer on account of, for instance, an interchange of the one part of the device .with a condenser having an aperture. diaphragm. With a view to illuminating the object under examination by means of a pencil of illumination rays which is inclined, instead of symmetrical, to the axis of the illumination system, it is convenient to so mount the diaphragm on its support as to be displaceable at right angles to and rotatable about this axis, the pencil of the incident illumination rays being, accordingly, adjustable in a simple manner to any azimuth and angle of incidence.

'The accompanying drawing shows in partsectional elevation a constructional example of the new' illumination device and a miscroscope.

The-microscope shown in the drawing has a horse-shoe base I on which is mounted a pillar 2 supporting a stage 3 and connected to a bracket 4. this bracket 4 are connected the optical observation parts, viz. arevoluble'objective carrier 5 provided with objectives 6, and a head 1 rotatable about the optical axis and fast with an inclined eye-piece tube 8. Below the stage 3, the pillar 2 has a slide II, which is displaceable at right angles to the surface of the stage 3 by means of a pinion 9 and a rack Ill, and a sleeve l2 for holding one of the usual microscope mirrors. The slide II is so constructed as to hold in the Eligwn manner an-exchangeable carrier i3 conta' g a microscope condenser.

The microscope base I contains a housing H which extends into the horse-shoe aperture. In

this housing "I4 is. mounted an incandescent lamp l5 and a lamp condenser It. That part of the housing I! which is below the stage 3 contains a prism l1 deflecting the pencil of illumination rays upwardly at right angles. Above the prism I1 is a guide ltfor a slide changer IS. A slide guide 20 is provided with a mounting 2| for a collecting lens 2|. Said mounting 2| is fixed to the slide guide 20, and both these parts are rotatable in the slide changer is about the axis of the lens 2| ,axial movement being prevented by a ring 2| threaded on the mounting 2|. In the slide guide 20, a slide 22 can be displaced at right angles to the axis of the lens 2| by means of a spindle 23. The slide 22 supports an iris diaphragm 24 provided with a mount 25 for light filters 26. v

The remaining part of the illumination device constitutes another constructional part, which is disposed in a housing 21. The optical elements in this housing 21 are a three lens-eondenser- 28 and a pancratic reversing system which consists of two convergent lenses 2i displaceable along the optical axis and a stationary divergent lens so disposed between the said lenses 29. Displacements of the lenses 29 are eflected by means of a milled head 3|. The housing 21 is screwed to the carrier ll.

when the device is in use, the carrier I21 fast with the housing 21 is heldby the slide I l. Rotating the pinion 9 causes the slide II to raise the carrier I! to such an extent that the frontlens of the microscope condenser 2! assumes its correct position'in the aperture in the stage 3. 'The mount of the lamp condenser It acts as a.

luminous-field diaphragm, and the iris diaphragm 24 serves as an aperture diaphragm. The lamp condenser l8 images the filament or the incandescent lamp l5 approximately in the plane of the aperture diaphragm 24, and the reversing system 28, 30 images this image in the entrance aperture of the microscope condenser 28. The

' image of the luminous field is'iniaged by the collecting lens 2| in the neighbourhood of the reversing system 29, tlL and the microscope condenser images this other image in the plane of the object. The image of the aperture diaphragm 24 lying in the entrance aperture of the microscope condenser 28, lateral displacements of the diaphragm 24 by means of the spindle 23 produce the sensation of a diaphragm situate in the entrance aperture being laterally displaced. Displacing the slide 22 from medial position entails, accordingly, a radial displacement of the pencil of imaging rays entering the microscope condenser 28, or, in other words, an inclination of the pencil of the rays illuminating the object. Accordingly, this inclined pencil can be given any desired azimuth by rotation of the lens mounting 21 and, consequently, of the slide guide 20 in the slide changer l9. 1

Whe'n dark-field observation is to be effected by means'ot the microscope, the carrier l8 and the housing 21 are replaced by a carrier l3 provided with a dark-field condenser. The slide changer I9 is removed from its guide l8, and observations are eflected' in the known manner through the agency of the in ndescent lamp l5. In contrast to the usual practice of placing a source of light outside the microscope, which genergllyrenders impossible observation from that side of the eye-piece which is remote from the bracket 4, the position the source of light assumes I source of light outside the microscope, for instance an arc-lamp, provided of. course that the sleeve l2 holds one of the usual microscope mirrors.

We claim:

1. In a microscope having an optical system comprising an objective and adapted to image 0 'iects on an enlarged scale, a device for illuminating said objects by transa base, a stand, and

mitted light, said device comprising two tubular housings and means for restricting of the pencil of illumination rays, the axes of said housings intersecting each other, one of said two housings being molmted in said base and containing a source 01' light, alamp condenser for producing an image of said source of light, the optical axis to the axis of said one housing, and a reflecting system for deviating the axis of the pencil of light rays into coincidence with the axis of said objective, the axis of the other of said housings being parallel to the axis of said objective, said other housing being attached to said stand and containing an optical reversing system of the pancratic type and a microscope condenser, the optical axes of said reversing system and said microscope condenser coinciding-with the axis of said objective, said reversing system and said microscope condenser being so disposed relatively to each other that the image produced by said reversing system of first said image lies in the entrance aperture of said microscope condenser, the said means comprising guiding means connected to the base of said microscope, a support the aperture of said lamp-condenser being parallel v 

